Chewable tablets are taken slowly by chewing or sucking in the mouth, and enable a pharmaceutical contained therein to be orally administered without water. Chewable tablets now on the market, however, may cause discomfort (e.g. roughness or dustiness) during or after ingestion, posing the problem of poor intrabuccal sensations. Particularly when a metal salt such as a calcium, magnesium or aluminum salt is incorporated, a marked discomfort arises. This is a serious problem for chewable tablets which remain in the mouth for a long time as compared with other preparations. By contrast, success in improving the sensations during or after ingestion were achieved by adjusting the particle sizes of the ingredients incorporated (Japanese Laid-Open Patent Publication No. 203332/89). This measure is not highly preferred for manufacture, because it increases the number of manufacturing steps. Poor intrabuccal sensations due to a calcium salt were also relieved by containing low viscosity hydroxyalkyl cellulose and high viscosity hydroxyalkyl cellulose (Japanese Laid-Open Patent Publication No. 306229/93). However, the effect obtained is not entirely satisfactory. Attempts have been made to improve the intrabuccal sensations by combining various additives such as sweeteners, acidic ingredients, taste correctives, polymeric compounds and essential oils of crude drugs. In such cases, the additive is needed in an amount of not less than 1.5 to 2 times the amount of the gastrointestinally active ingredient, thus making the size of the chewable table itself large. Such large tablets are difficult to take. In addition, a special machine for producing large tablets is required, posing an economic problem.
As described above, gastrointestinal chewable tablets thus far known have been unsatisfactory in intrabuccal sensations, and there has been a demand for correcting such a drawback.